The present invention is directed to an automatic container latch and method of operating same, and more specifically, toward a gravity-operated container latch that shifts from a latched to an unlatched position when a container is pivoted from a rest orientation to a dumping orientation.
Facilities that produce substantial amounts of waste often dispose it in large trash receptacles that are emptied periodically by a trash truck. Generally, the receptacles are formed from steel or a similar material and are too heavy to lift manually, especially when full. A trash truck having a special lift is thus normally used to raise and empty these containers. To lift a container, the truck parks so that fingers on a lift arm on the truck can be inserted into special openings on the trash receptacle. The lift arm is then raised in an arc toward an opening in the top or side of the truck and tipped toward the opening until all trash in the receptacle falls out. Such trash receptacles often have lids hingedly connected to the their main bodies, and the lids pivot open as the receptacle is tipped. After the receptacle has been emptied, the lift arm returns it to an upright position and lowers it to the ground.
Certain trash receptacles are used with trash compactors that have a ram for forcing trash into the receptacle to reduce its volume and increase its density. These rams often push trash into a receptacle from one side, and it is thus necessary to hold the receptacle lid securely in place or the compacted trash will be forced upward by the ram and rise up and out of the receptacle. Even small gaps between the receptacle and its lid may allow unacceptable amounts of trash to escape, especially when the trash has a significant liquid component. These receptacles therefore generally include a latching mechanism that holds the receptacle lid securely closed and allows little or no gap between the container body and the lid even when trash therein is being compressed.
When such containers are to be emptied by a trash truck, a truck driver or another person must approach the trash container, release the latch, dump the receptacle into the truck and then return to re-latch the container. This latching and unlatching significantly reduces the advantages of using an automatic trash collection truck.
Automatic latch releases are known from the prior art which may be opened and closed by a radio transmitter, for example. However, such electronic solutions can be expensive to implement and require that the operator of a trash truck carry one or more transmitters for opening any container on his route. Also know from the prior art are containers with latches that are actuated by gravity when the container tips from an upright to a dumping position. Most of these latches, however, are designed either to keep a container lid closed under high wind conditions or to prevent unauthorized persons from gaining access to the trash container and are not suited for use with a compactor receptacle that is subjected to significant internal pressures during use. For example, U.S. Pat. No. 5,094,487 shows a trash receptacle comprising a body and a lid that has a housing mounted on one of the body sidewalls. A hook depends from the lid and extends into the housing when the lid is closed and the container is resting on its bottom. A freely pivotable rod inside the housing includes a projection that engages the hook when the container is horizontal and that pivots away from the hook to release it when the container is tipped. However, the clearances required by this arrangement do not allow the lid to be held completely shut, and thus the lid would open under the application of pressure from within and force trash out of the top thereof. U.S. Pat. No. 4,155,584 shows an automatic lock for a container that includes a pivotable weight which swings though an arc and impacts against a latch to release the latch when the container is inverted. This complex arrangement requires that the weight impact against a release with sufficient force to unhook the latch. If the lid of a receptacle is forced upwardly by pressure from compacted trash inside the container, the unlatching device might not function properly. Furthermore, the swinging arm impacting against a release is likely to lead to wear and may require the device to be replaced or repaired with some frequency.
There is thus a need for a container latch that automatically unlatches when the container is pivoted from a resting orientation to a dumping orientation and which re-latches when the container is returned to its resting orientation, which latch functions even when the contents of the container are under pressure and which holds the lid of the container securely closed with little or no gap between the lid and the container.
These problems are overcome by the subject invention which comprises an automatic latching device for a container such as a trash receptacle. The subject invention is particularly useful for securing the lids of trash receptacles, especially trash receptacles that are used in conjunction with a trash compactor that forces trash into the container under pressure; however the invention could be practiced with other types of dumpable receptacles without departing from the scope of this invention. Thus, while the container described herein is generally referred to a trash receptacle, the use of invention is in no way limited to such containers.
In the preferred embodiment, the invention is a container having a pivotable lid with a projection near its free end. This projection is engaged by a hook pivotally mounted on the sidewall of the container body. When the hook engages the projection, the lid is held firmly against the top of the container body. Furthermore, because the hook is pivotally mounted, it can resist upward pressure on the lid such as may be exerted when the container receives trash under pressure from a compactor. Also attached to the container sidewall is a weight mounted for pivotal movement about an axis located near the edge of the weight which weight assumes a first position when the container is in an upright position and a second position when the container tips toward a dumping position. The weight is connected to the hook by a rigid rod, and when the weight pivots, it moves the rod and the hook to release the hook or reengage it with the projection. As described more fully hereinafter, the arrangement of the rod and the weight increases the effective force applied against the hook to provide for secure, positive latching.
Also according to the preferred embodiment, the weight is mounted in a bi-stable manner so that once it becomes unbalanced it shifts from the first position to the second position and does not remain in an intermediate position for a significant amount of time. This helps ensure that the latch is positively engaged or disengaged and not left in some intermediate position. In addition, two stops are provided to limit the pivotal movement of the weight. The relationship between the center of gravity of the weight and the weight""s axis of rotation is selected so that once the center of gravity passes over the pivot axis, the weight falls a further distance and impacts against a stop. Thus when the container moves from a rest orientation to a dumping orientation, the weight shifts when the container is tipped at a first angle, and when the container is moved from a dumping orientation to a rest orientation, the weight shifts back when the container is tipped at a second angle. This allows the latch to be latched and unlatched at different points in the travel of the container from a rest orientation to a dumping orientation, depending on the direction that the container is being tipped. Preferably, the lid is kept latched until the container opening is nearly vertical or until the container is inverted to ensure no trash falls from the container before it is properly positioned. However, the lid cannot be re-latched until the lid falls back onto the container body under the force of gravity when the container is relatively horizontal.
It is therefore a principal object of the present invention to provide a dumpable container having an automatic latch release.
It is another object of the present invention to provide a gravity-operated latch for a lidded container.
It is a further object of the present invention to provide a gravity-operated latch for a dumpable container that includes a bi-stably mounted actuating weight.
It is still another object of the present invention to provide a gravity-operated latch for a dumpable container that includes a weight positively coupled to a fastener to positively shift the fastener between first and second positions as the weight moves.
It is still a further object of the present invention to provide a method of positively latching and unlatching a container using a gravity-operated actuator.
It is yet another object of the present invention to provide a method of latching a lid to a container body in a manner that holds the lid securely against the container body using a gravity-operated actuator.
In furtherance of these objects, a container is provided that comprises a body having an interior, an exterior, a sidewall and a top opening, and a lid having a first end hingedly connected to the body and a second end, the lid being shiftable between a closed position covering the top opening and an open position allowing access to the interior. The lid is secured by a fastener and the fastener is positively shifted between a securing and a releasing position by a gravity-operated actuator that includes a weight mounted on the body exterior for bi-stable movement between a first position and a second position with respect to the sidewall, and a rigid link connecting the weight to the fastener so that the fastener is shifted from the securing position to the releasing position when the weight shifts from the first position to the second position.
The invention further comprises a container adapted to be moved from a rest orientation to a dump orientation during a dumping operation including a body having an interior and a top opening into the interior and a lid having a first end hingedly connected to the body and shiftable between a closed position covering the top opening and an open position allowing access to the interior. The container assumes a first angular orientation with respect to the ground when it is in a rest orientation and a second angular orientation with, respect to the ground when it is in the dump orientation. The container also includes a fastener for holding the lid in the closed position and substantially preventing movement of the lid when pressure is applied against the lid from the interior and an actuator for positively shifting the fastener between a securing and a releasing position. The actuator includes a weight pivotably mounted on the body for movement to a first position with respect to the sidewall when the container has a first angular orientation with respect to the ground and to a second position with respect to the sidewall when the container has a second angular orientation with respect to the ground and a link rigidly connected between the weight and the fastener for transferring substantially all motion of the weight to the fastener.
The invention further comprises a method of latching and unlatching a container by changing the orientation of the container with respect to the ground including the steps of providing a container having a lid, providing a fastener shiftable between a first position for securing the lid to the container and a second position for releasing the lid, mounting a weight on the container to pivot bi-stably between first and second positions in response to changes in the orientation of the container, positively coupling the weight to the fastener, pivoting the container in a first direction until the weight shifts to the second position, dumping the contents of the container and pivoting the container from the second position to the first position until the weight shifts to the first position.